U.S. patent number 7,856,291 [Application Number 11/856,133] was granted by the patent office on 2010-12-21 for cleaning robot and method for controlling the same.
This patent grant is currently assigned to LG Electronics Inc.. Invention is credited to Hyeong Shin Jeon, Yong Gyu Jung.
United States Patent |
7,856,291 |
Jung , et al. |
December 21, 2010 |
Cleaning robot and method for controlling the same
Abstract
A cleaning robot may be provided having a case and a sensor
assembly. The sensor assembly may include a sensor hole having a
first opening provided at an outer surface of the case and a second
opening provided inwardly of the first opening, with respect to a
center of the case. Additionally, the sensor assembly may include a
sensor element configured to receive a signal and the sensor
element may be provided inwardly of the first opening.
Inventors: |
Jung; Yong Gyu (Inchun-si,
KR), Jeon; Hyeong Shin (Kyungsangnam-do,
KR) |
Assignee: |
LG Electronics Inc. (Seoul,
KR)
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Family
ID: |
39304008 |
Appl.
No.: |
11/856,133 |
Filed: |
September 17, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080091303 A1 |
Apr 17, 2008 |
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Foreign Application Priority Data
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Oct 13, 2006 [KR] |
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10-2006-0099858 |
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Current U.S.
Class: |
700/258; 701/23;
367/20; 901/47; 367/104; 73/649; 367/98; 700/250 |
Current CPC
Class: |
G05D
1/0255 (20130101); G05D 2201/0215 (20130101) |
Current International
Class: |
G05B
19/04 (20060101); G01C 22/00 (20060101) |
Field of
Search: |
;367/98,104,20 ;15/49.1
;73/40.5A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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20-0412601 |
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Mar 2006 |
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KR |
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20412601 |
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Mar 2006 |
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KR |
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Primary Examiner: Black; Thomas G
Assistant Examiner: Olsen; Lin B
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
What is claimed is:
1. A cleaning robot comprising: a case; and a sensor assembly, the
sensor assembly comprising: a sensor hole having a first opening
provided at an outer surface of the case, a second opening provided
inwardly of the first opening, and a sensor mount provided inwardly
of the second opening, with respect to a center of the case; and a
sensor element configured to detect an obstacle, wherein the sensor
element is at the sensor mount, wherein Hh defines a minimum
distance from the first opening to the second opening, ds defines a
diameter of the sensing element, and the ratio Hh/ds is about 1.1
to about 1.8.
2. The cleaning robot of claim 1, wherein the second opening has a
cross-sectional area which is smaller than a cross-sectional area
of a mount opening of the sensor mount.
3. A cleaning robot comprising: a case; and a sensor assembly, the
sensor assembly comprising: a sensor hole having a first opening
provided at an outer surface of the case, a second opening provided
inwardly of the first opening, and a sensor mount provided inwardly
of the second opening, with respect to a center of the case; and
wherein the sensor hole further comprises: a sensor wall extending
inwardly from the first opening to the second opening, an outer end
of the sensor wall opening to an outer side of the case, and an
inner end of the sensor wall opening to an interior of the case,
and wherein the slope of the sensor wall, with respect to an axis
passing through the centers of the first and second openings, is
about 0.0 to about 18.0 degrees.
4. The cleaning robot of claim 3, wherein the second opening has a
cross-sectional area which is smaller than a cross-sectional area
of a mount opening of the sensor mount.
5. The cleaning robot of claim 3, wherein Hh defines a minimum
distance from the first opening to the second opening, ds defines a
diameter of the sensing element, and the ratio Hh/ds is about 1.1
to about 1.8.
6. The cleaning robot of claim 3, wherein dh defines a diameter of
the second opening, ds defines a diameter of the sensing element,
and the ratio dh/ds of the sensor is about 0.3 to about 1.0.
7. A cleaning robot comprising: a case; and a sensor assembly, the
sensor assembly comprising: a sensor hole having a first opening
provided at an outer surface of the case, a second opening provided
inwardly of the first opening, and a sensor mount provided inwardly
of the second opening, with respect to a center of the case; and a
sensor element configured to detect an obstacle wherein the sensor
element is provided at the sensor mount, wherein dh defines a
diameter of the second opening, ds defines a diameter of the
sensing element, and the ratio dh/ds of the sensor is about 0.3 to
about 1.0.
8. The cleaning robot of claim 7, wherein Hh defines a minimum
distance from the first opening to the second opening, ds defines a
diameter of the sensing element, and the ratio Hh/ds is about 1.1
to about 1.8.
9. A cleaning robot comprising: a case; and a sensor assembly, the
sensor assembly comprising: a sensor hole including a sensor wall
which extends inwardly from a first opening provided at an outside
of the case and a second opening provide at an inside of the case;
and a sensing element including a transmitter and a receiver,
wherein at least one of the transmitter and the receiver is
provided inwardly of the first opening, wherein a protrusion is
formed at the sensor wall and a groove into which the protrusion is
inserted is formed at the case such that the sensor hole is
assembled to the case.
10. A cleaning robot, comprising: a case; and a sensor assembly,
the sensor assembly comprising: a sensing element which transmits
or receives a predetermined signal; and a sensor hole provided on
the case, the sensor hole having a sensor wall, a first opening
provided at an outer surface of the case, and a second opening
provided inwardly of the first opening with respect to a center of
the case, wherein the sensor hole is configured to restrict a
radiation range of the predetermined signal, wherein a protrusion
is formed at the sensor wall and a groove into which the protrusion
is inserted is formed at the case such that the sensor hole is
assembled to the case.
11. The cleaning robot of claim 10, wherein the sensing element is
provided inwardly of the first opening with respect to a center of
the case.
12. The cleaning robot of claim 10, wherein a cross-sectional area
of the sensor hole increases as the sensor hole extends from the
second opening towards the first opening.
Description
This application claims the benefit of Korean Patent Application
No. 10-2006-0099858, filed on Oct. 13, 2006, the entire contents of
which are hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cleaning robot and a method for
controlling the same. More particularly, the present invention
relates to a cleaning robot which easily discriminates or
(discerns) between a signal reflected from an obstacle and a direct
noise, and a method for controlling the same.
2. Description of the Conventional Art
A cleaning robot is a kind of mobile robot which absorbs dust and
foreign material while moving by itself in a certain space such as
a house or an office.
The aforementioned cleaning robot includes a traveling means
including right and left wheel motors for moving the cleaning
robot, a detection sensor for detecting and avoiding a variety of
obstacles within a cleaning area, and a control means for
controlling the traveling means and the detection sensor to perform
cleaning, as well as the components of a general vacuum cleaner
which absorbs dust and foreign material.
FIG. 17 is a schematic view of an ultrasonic sensor of a cleaning
robot according to the conventional art. FIG. 18 is a graph
illustrating signals obtained by the ultrasonic sensor of FIG.
17.
As illustrated in FIGS. 17 and 18, the cleaning robot according to
the conventional art includes a case 1 and an ultrasonic sensor
installed on the surface of the case 1. The ultrasonic sensor
includes a transmitter portion 2 and receiver portion 3.
The transmitter portion 2 and the receiver portion 3 are installed
spaced by a predetermined distance from each other, and recognizes
obstacles 5 and 6 by receiving an ultrasonic wave transmitted from
the transmitter portion 2.
If the transmitter portion 2 transmits a predetermined ultrasonic
wave, this generates a direct noise 7 flowing along the case 1, as
well as the ultrasonic wave transmitted to the outside of the case
1.
However, as illustrated in FIG. 18, there is a problem that the
receiver portion 3 is unable to discriminate (or discern) between
the direct noise 7 and an obstacle signal 8 that are received at a
similar time because the receiver portion 3 receives the direct
noise 7 transmitted along the surface of the case 1 and the signal
8 reflected from the spaced obstacle 5.
Therefore, the cleaning robot according to the conventional art has
the problem of not being able to recognize the obstacle 5 as far as
the position spaced by a predetermined distance from the case 1 due
to the direct noise 7.
SUMMARY OF THE INVENTION
In one aspect of the present invention, a cleaning robot is
provided which easily discriminates or discerns between a signal
reflected by an obstacle and a direct noise, and a method for
controlling the same. In this regard, the cleaning robot may
dissolve (or eliminate) an obstacle un-measurable area by
discriminating (or discerning) between a direct noise and an
obstacle signal, and a method for controlling the same. More
particularly, the cleaning robot may be provided having a sensor
hole disposed or provided so as to reduce the amplitude of a direct
noise as compared to a signal reflected from an obstacle.
In one non-limiting embodiment, the cleaning robot may include a
case and a sensor assembly. The sensor assembly may include a
sensor hole having a first opening provided at an outer surface of
the case and a second opening provided inwardly of the first
opening, with respect to a center of the case. Additionally, the
sensor assembly may also include a sensor element configured to
receive a signal. Further, the sensor element may be provided
inwardly of the first opening.
In an additional aspect, the sensor hole may include a sensor mount
provided at the second opening, and the sensor element may be
provided at the sensor mount. Additionally, the sensor element may
include plurality of sensor elements including a transmitter and a
receiver. In this regard, the sensor hole may include a plurality
of sensor holes having corresponding sensor mounts, and the
transmitter and receiver may be provided at a corresponding sensor
mount.
In an additional aspect, the sensor hole may also include a sensor
wall extending inwardly from the first opening to the second
opening, an outer end of the sensor wall opening to an outer side
of the case, and an inner end of the sensor wall opening to an
interior of the case. Additionally, the sensor hole may also
include a sensor mount provided at the second opening. In this
regard, the sensor wall may be communicatingly connected to the
sensor mount and second opening.
In yet still another aspect, the second opening may have a
cross-sectional area which is smaller than a cross-sectional area
of a mount opening of the sensor mount. Additionally, Hh may define
a minimum distance from the first opening to the second opening, ds
may define a diameter of the sensing element, and the ratio Hh/ds
may be about 1.1 to about 1.8. In a further feature, the slope of
the sensor wall, with respect to an axis passing through the
centers of the first and second openings, may be about 0.0 to about
18.0 degrees.
According to another aspect, dh may define a diameter of the second
opening, ds may define a diameter of the sensing element, and the
ratio dh/ds of the sensor may be about 0.3 to about 1.0.
Additionally, a cross-sectional area of the sensor hole may
increase as the sensor hole extends from the second opening towards
the first opening. Further, the case may have a generally circular
shape. Additionally, at least a portion of the sensor hole may have
a truncated generally conical shape.
In an additional aspect, the sensor hole may include a plurality of
sensor holes spaced at an interval and positioned at a
predetermined angle with respect to the case. In yet still another
feature, the sensor hole may be formed integral with the case.
Additionally, the sensor hole may be mounted to the case.
According to another feature, the sensor hole may protrude outside
of the case. Additionally, the sensor element may be an ultrasonic
sensor. Further, at least one of the transmitter and the receiver
may be provided inwardly of the first opening. Thus, in accordance
with the non-limiting features of the present invention, the sensor
hole may be configured to restrict a radiation range of the
predetermined signal.
In another non-limiting embodiment, a method for controlling a
cleaning robot, may include providing a case having a sensing
element, the sensing element may include a transmitter configured
to transmit a signal and a receiver configured to receive a
transmitted signal. Additionally, the controlling method may
include comparing the amplitude of the transmitted signal received
by the receiver to a predetermined level. In this regard, it may be
determined that the transmitted signal is a signal reflected by an
obstacle when the amplitude of the transmitted signal is greater
than the predetermined level, and that the signal is a direct noise
when the amplitude of the transmitted signal is less than the
predetermined level.
In an additional aspect, when a plurality of signals is inputted
into the receiver and at least one of the plurality of input
signals is higher than the predetermined level, the at least one of
the input signals is determined to be a signal reflected from an
obstacle. Additionally, the amplitude of the transmitted signal
received by the receiver may be compared to a predetermined level,
after a predetermined signal corresponding to the predetermined
level is transmitted by the transmitter.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is further described in the detail
description which follows, in reference to the noted plurality of
drawings, by way of non-limiting examples of preferred embodiments
of the present invention, in which like characters represent like
elements throughout the several views of the drawings, and
wherein:
FIG. 1 is a perspective view illustrating a cleaning robot
according to a first embodiment of the present invention;
FIG. 2 is a perspective view illustrating an internal structure of
the cleaning robot as illustrated in FIG. 1;
FIG. 3 is a perspective view illustrating the bottom part of the
cleaning robot as illustrated in FIG. 1;
FIG. 4 is a top perspective view illustrating a suction nozzle unit
of the cleaning robot as illustrated in FIG. 1;
FIG. 5 is a bottom perspective view illustrating a suction nozzle
unit of the cleaning robot as illustrated in FIG. 1;
FIG. 6 is a cross sectional view of the cleaning robot as
illustrated in FIG. 1;
FIG. 7 is a schematic cross sectional view illustrating an
ultrasonic sensor of the cleaning robot as illustrated in FIG.
1;
FIG. 8 is a front view of the ultrasonic sensor as illustrated in
FIG. 7;
FIG. 9 is a cross sectional view of a sensor hole as illustrated in
FIG. 7;
FIG. 10A is a view illustrating a radiation range of the ultrasonic
sensor according to the conventional art;
FIG. 10B is a view illustrating an radiation range of the
ultrasonic sensor according to the present invention;
FIG. 11 is a graph illustrating a transmission signal and a
reception signal of the ultrasonic sensor as illustrated in FIG.
7;
FIG. 12 is a graph illustrating a direct noise with respect to the
diameter ds of the sensor and the depth Hh of the sensor hole as
illustrated in FIG. 9;
FIG. 13 is a graph illustrating a direct noise with respect to the
diameter ds of the sensor and the diameter dh of an inner opening
as illustrated in FIG. 9;
FIG. 14 is a graph illustrating a direct noise with respect to a
slope a of the sensor hole as illustrated in FIG. 9;
FIG. 15 is a cross sectional view illustrating a sensor hole of a
cleaning robot according to another embodiment of the present
invention;
FIG. 16 is a cross sectional view illustrating a sensor hole of a
cleaning robot according to still another embodiment of the present
invention;
FIG. 17 is a schematic view where an ultrasonic sensor of a
cleaning robot according to the conventional art is installed;
and
FIG. 18 is a graph illustrating a signal obtained by the ultrasonic
sensor of FIG. 17.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The particulars shown herein are by way of example and for purposes
of illustrative discussion of the embodiments of the present
invention only and are presented in the cause of providing what is
believed to be the most useful and readily understood description
of the principles and conceptual aspects of the present invention.
In this regard, no attempt is made to show structural details of
the present invention in more detail than is necessary for the
fundamental understanding of the present invention, the description
taken with the drawings making apparent to those skilled in the art
how the several forms of the present invention may be embodied in
practice.
Several non-limiting embodiments of a cleaning robot according to
the present invention are explained hereinafter.
FIG. 1 is a perspective view illustrating a cleaning robot
according to a first embodiment of the present invention. FIG. 2 is
a perspective view illustrating an internal structure of the
cleaning robot as illustrated in FIG. 1. FIG. 3 is a perspective
view illustrating the bottom part of the cleaning robot as
illustrated in FIG. 1.
As illustrated in FIGS. 1 to 3, the cleaning robot 100 may include
a case 110 forming the outer appearance (e.g., the exterior of the
case), an air suction device 120 installed inside the case 110, the
air suction device 120 may be configured to suction air at the
lower part of the case 110 and to discharge the air out of the case
110, a suction nozzle unit 130 may be installed on the case 110 and
connected to the air suction device 120. The air suction device 120
may have an agitator 134 installed therein for providing a flow
path for suctioning external air and floating dust on the floor,
and a dust collector for separating foreign material suctioned by
the suction nozzle unit 130 from air and collecting the dust.
The case 110 may be formed in a generally round disk (or circular)
shape having a predetermined height.
The air suction device 120, the suction nozzle unit 130, and the
dust collector 140 which communicates with the suction nozzle unit
130 may be provided inside the case 110.
In addition, a sensor (not shown) for sensing the distance to an
indoor wall or an obstacle and a bumper 112 for cushioning a shock
upon collision may be provided on the case 110. Left and right
driving wheels 150 and 160 for moving the cleaning robot 100 may be
provided at lower parts of the case 110, respectively.
The left and right driving wheels 150 and 160 may be configured to
rotate by a left wheel motor 151 and a right wheel motor 161 that
are controlled by a controller 180. The cleaning robot moves
forward and backward, turns, and rotates depending on the rotation
direction and rotation ratio of the left and right wheel motors 151
and 161.
At least one auxiliary wheel 170 may be provided on the bottom of
the case 110, thereby preventing the bottom surface of the case 110
from direct contact with the floor thereby minimizing friction
between the cleaning robot and the floor.
The internal construction of the cleaning robot 100 will be
described in more detail. A controller 180 having various mounting
parts disposed therein for controlling the driving of the cleaning
robot 100 may be provided at the front side of the case 110, and a
battery 190 for supplying power to each part of the cleaning robot
may be provided at the rear side of the controller 180.
The air suction device 120 which generates an air suction force may
be installed at the back of the battery 190, and a dust collector
mounting portion 140a may be installed at the back of the air
suction device so as to install the dust collector 140 thereon. The
dust collector 140 may be structured such that it is fixed to the
dust collector mounting portion 140a. For example, the dust
collector 140 may be detachably connected to the mounting portion
140a
The suction nozzle unit 130 may be provided at the lower side of
the dust collector 140, thereby suctioning air and foreign material
on the floor.
The air suction device 120 may include a motor (not shown)
installed between the battery 190 and the dust collector 140 and
electrically connected to the battery 190 and a fan (not shown)
connected to a rotary shaft of the motor for forcing an air
flow.
The suction nozzle unit 130 may be installed so as to face the
bottom of the case 110 so that a suction port 132 is exposed to the
lower side of the case 110.
As discussed above, the suction nozzle unit 130 may suction foreign
material on a surface, e.g., on the floor of an indoor space, and
will be described in more detail with reference to FIGS. 4 and
5.
FIG. 4 is a top perspective view illustrating a suction nozzle unit
130 of the cleaning robot as illustrated in FIG. 1. FIG. 5 is a
bottom perspective view illustrating a suction nozzle unit of the
cleaning robot as illustrated in FIG. 1. FIG. 6 is a cross
sectional view of the cleaning robot as illustrated in FIG. 1;
Referring to FIGS. 4 to 6, the suction nozzle unit 130 includes a
nozzle case 131 having a suction port 132 and an exhaust port 133
formed therein. The nozzle case 131 and the suction port 132 are
configured to be installed in the case 110, and an agitator 134 may
be installed inside the nozzle case 131, i.e., at the suction port
132 side, for agitating dust on a surface (e.g., a floor).
The suction port 132 may be formed to communicate with the lower
surface of the case 110, i.e., so as to face the floor, while the
exhaust port 133 may be formed to communicate with the dust
collector 140, thereby guiding the air sucked from the suction port
132 to the dust collector 140.
An auxiliary wheel 131a is installed on the lower surface of the
nozzle case 1313 so as to prevent the suction port 132 from tightly
contacting to the floor.
The suction port 132 suctions foreign material stacked on the floor
by an air suction force generated by the air suction device 120,
and the exhaust port 133 may be connected to the dust collector 140
through a communicating tube 133a.
A plurality of suction grooves 132a may be formed on the lower
surface of the nozzle case 131 in a forward and backward traveling
direction of the cleaning robot. The suction grooves 132a may form
a passage which prevents the suction port 132 from being blocked by
foreign material on the floor at the front of the nozzle case 131
a, thereby preventing an overload of the motor provided on the air
suction device 120.
Both ends of the agitator 134 may be connected to both side walls
of the suction port 132 so as to be rotatable, and rotates or
angularly reciprocates so as to shake the dust off the floor or
carpet and floating it in the air.
A plurality of blades 134a provided in a spiral direction may be
formed on the outer circumferential surface of the agitator 134,
and a brush may be installed between the blades 134a formed in a
spiral shape.
For the operation of the agitator 134, an agitator motor 134b and a
belt 134c functioning as power transmission equipment for
transmitting power of the agitator motor 134b to the agitator 134
may be provided on the nozzle case 131.
When a rotation force of the agitator motor 134b is transmitted to
the agitator 134 through the belt 134c, the agitator 134 may sweep
the foreign material on the floor to the suction port 132 while
rotating.
FIG. 7 is a schematic cross sectional view illustrating an
ultrasonic sensor of the cleaning robot as illustrated in FIG. 1.
FIG. 8 is a front view of the ultrasonic sensor as illustrated in
FIG. 7. FIG. 9 is a cross sectional view of a sensor hole as
illustrated in FIG. 7.
As illustrated in FIG. 7, sensor holes 202 and 204 may be formed
concave inward and provided (or formed) on the case 110, and an
ultrasonic sensor 210 used as a sensor unit (i.e., sensing
element)_may be disposed on (or provided at) the sensor hole 202 in
order to detect an obstacle to be found during the traveling of the
cleaning robot 100.
The ultrasonic sensor 210 may include a transmitter 212 configured
to generate an ultrasonic wave and a receiver 214 configured to
receive the ultrasonic wave reflected from an obstacle 5.
The transmitter 212 and the receiver 214 may be installed (e.g.,
mounted or otherwise provided) at the sensor holes 202 and 204,
respectively, formed (or provided) on the case 110.
As illustrated in FIGS. 7 to 9, the sensor holes 202 and 204 of the
case 110 may be formed in a conical shape (e.g., a truncated
generally conical shape) whose diameter increases as the sensor
holes 202 and 204 extend toward the outside of the case.
Additionally, the wall 203 which provides the sensor holes 202 and
204 with their conical shapes, may have a predetermined slope a
with respect to the center of the sensor holes 202 and 204.
The ultrasonic sensor 210 may be installed on the sensor holes 202
and 204, the sensor holes 202 and 204 being configured to restrict
the angle of a signal transmitted to or received from the
ultrasonic sensor 210.
Therefore, the sensor holes 202 and 204 may be formed in such a
shape in which the area of a cross section increases. For example,
in one-limiting embodiment, the sensor holes 202 and 204 may be
formed having a trumpet shape (e.g., a truncated generally conical
shape) which may be formed at an angle of 2.alpha..
The sensor holes 202 and 204 may include the sensor hole wall 203
being formed integrally with the case 110 and longitudinally
extended to the inside, an outer opening 205 may be provided (or
positioned) at the outer end of the sensor hole wall 203 and
exposed to the outer surface of the case 110, an inner opening 206
may be provided (or positioned) at the inner end of the sensor hole
wall 203 and formed at the inside of the case 110, and an
installation portion (i.e., sensor mount) 207 may be connected to
the inner end of the sensor hole wall 203 and provided with the
ultrasonic sensor 210 installed therein.
The surface connecting the outer opening 205 to the inner opening
206 may be continually formed. The installation portion 207 may be
stepped from the inner opening 206, and formed such that the
transmitter 212 or receiver 214 of the ultrasonic sensor 210 can be
inserted and fitted therein.
Therefore, the installation portion 207 may be wider than the inner
opening 206. Additionally, the inner and outer openings 205 and
206, and the installation portion 207 may be formed integral with
the case 110.
Here, the diameter of the inner opening 206 may be dh, the diameter
of the transmitter portion 212 or receiver portion 214 of the
ultrasonic sensor 210 may be ds, the shortest distance from the
inner opening 206 to the outer opening 206 may be Hh, and the angle
between the inner opening 206 and the outer opening 205 may be the
slope .alpha..
Here, the diameter ds may be the diameter of the upper end of the
ultrasonic sensor 210 contacting the inner opening 206. However it
should be appreciated that the cross section of the ultrasonic
sensor 210 may be provided having any suitable shape. For example,
one of ordinary skill in the art would appreciate that the sensor
210 may have a square, rectangular, oval or any other suitable
shape. Thus, in this case the term diameter may refer to an
effective width (e.g., an average width) of the sensor 210)
Further, although the diameter ds may be used to represent the
ultrasonic sensor 210 having a generally cylindrical shape, the
diameter may be converted into a ratio equal to that of the
cylindrical type and calculated even if the ultrasonic sensor 210
having a cubical or other shapes (e.g., an effective diameter).
For example, in the case where the ultrasonic sensor 210 is
installed on the installation portion 207, the radiation range of a
signal transmitted from the transmitter portion 212 and the range
of a signal received by the receiver portion 214 decreases in
comparison with the conventional art, and the amplitude of a direct
noise directly transmitted to the receiver 214 from the transmitter
212 decreases.
At this time, the signal range of the ultrasonic sensor 210 may be
related to the slope .alpha., and the wider the slope, the more
advantageous it may be for measurement by the ultrasonic sensor
210.
Hence, this embodiment provides the range in which the angle of the
slope .alpha. is the largest and the direct noise it the
smallest.
FIGS. 10A and B are views illustrating a radiation range of the
ultrasonic sensor according to the embodiment as illustrated in
FIG. 7 and in the conventional art. FIG. 11 is a graph illustrating
a transmission signal and a reception signal of the ultrasonic
sensor as illustrated in FIG. 7. FIG. 12 is a graph illustrating a
direct noise with respect to the diameter ds of the sensor and the
depth Hh of the sensor hole as illustrated in FIG. 9. FIG. 13 is a
graph illustrating a direct noise with respect to the diameter ds
of the sensor and the diameter dh of an inner opening as
illustrated in FIG. 9. FIG. 14 is a graph illustrating a direct
noise with respect to .alpha. slope a of the sensor hole as
illustrated in FIG. 9.
As illustrated in FIG. 7, the ultrasonic sensor 210 according to
this embodiment may be inserted and installed into a sensor
installation portion 207 of the sensor holes 202 and 204. Since an
opened area of the sensor holes 202 and 204 may be restricted,
orientation may be given to a signal transmitted from the
ultrasonic sensor 210, as well as to a signal reflected and
received from the obstacle.
As illustrated in FIG. 7 or 11, when the transmitter 212 transmits
a predetermined signal {circle around (s)}, a direct noise may be
generated on the surface of the case 110 by the signal {circle
around (s)} generated by the transmitter 212, and the generated
signal may be radiated through the sensor hole 202.
An ultrasonic wave transmitted from the transmitter portion 212 may
refracted by the sensor hole 202 and transmitted to the sensor hole
204, and the direct noise may be generated by the refraction of the
ultrasonic wave.
Afterwards, the signal {circle around (s)} radiated through the
sensor hole 202 may be reflected by the surfaces of the obstacles 5
and 6, and the reflected signal may be transmitted to the receiver
214 of the sensor hole 204 ({circle around (1)}, {circle around
(2)}).
In addition, the receiver 214 receives the direct noise {circle
around (3)} transmitted through the surface of the case 110.
At this time, even when the time at which the signal {circle around
(1)} reflected from the obstacle 5 is received by the receiver 214
is the same as the time at which the direct noise {circle around
(3)} is received by the receiver portion 214, the amplitudes of the
signals {circle around (1)} and {circle around (3)} received by the
receiver 214 are different from each other.
That is, the reflected signal {circle around (1)} caused by the
obstacle 5 is larger than the signal caused by the direct noise
{circle around (3)} because the amplitude of the reflected signal
is attenuated when the direct noise {circle around (3)} is
transmitted along the case 110.
Therefore, the controller 180 of the cleaning robot 100 can
discriminate between the signal {circle around (1)} reflected by
the obstacle 5 and the direct noise {circle around (3)} by
comparing the amplitudes of the received signals {circle around
(1)} and {circle around (3)}, even when the signals are received at
the same time by the receiver 214.
Moreover, the controller 180 is able to discriminate more
definitely whether the received signals {circle around (1)} and
{circle around (2)} are signals reflected by the obstacles or not
by comparing the amplitudes of the signals {circle around (1)} and
{circle around (2)} reflected from the obstacles 5 and 6.
As illustrated in FIGS. 8, 9, and 12, the graph of FIG. 12 is a
graph illustrating the correlation between the ratio of the depth
Hh of the sensor holes 202 and 204 to the sensor diameter ds and
the direct noise, the graphs shown illustrating the amplitude of
the direct noise {circle around (3)}.
Hence, it can be seen in FIG. 12 that the amplitude of the direct
noise is the smallest when the magnitude of the slope .alpha. is
about 15 degrees, and that the greater the ratio Hh/ds between the
length Hh of the sensor holes and the sensor diameter ds, the less
the amplitude of the direct noise.
More particularly, it can be seen that the direct noise decreases
at about 1.1 to about 1.8, which is the area where the measurement
values are reduced. Preferably, the direct noise is the lowest in
the range where the slope .alpha. is about 15 degrees and the ratio
Hh/ds is about 1.6.+-.0.2.
Moreover, as illustrated in FIGS. 8, 9, and 13, in the case that
the slope a of the sensor holes 202 and 204 is positioned or
provided at about 15 degrees, the greater the ratio dh/ds of the
sensor diameter ds to the diameter dh of the inner opening 206, the
less the amplitude of the direct noise {circle around (3)} and the
detection angle of an obstacle.
For example, the detection angle of an obstacle may be wide and the
direct noise may be small. Thus, it can be seen that the direct
noise decreases when the ratio dh/ds of the sensor diameter ds to
the diameter dh of the inner opening 206 is about 0.3 to about 0.9,
more preferably, determined within the range of about
0.5.+-.0.1.
Furthermore, as illustrated in FIGS. 8, 9, and 14, it is
advantageous that the detection angle of an obstacle is wide and
the direct noise is low. Thus, the slope a of the sensor holes 202
and 204 can range from about 10 to about 22 degrees, or about
14.+-.2 degrees.
Therefore, referring to the graphs of FIGS. 12 to 14, the slope of
the sensor hole wall 203 forming the sensor holes 202 and 204 may
be about 14.+-.2 degrees and the ratio dh/ds of the sensor diameter
ds to the diameter dh of the inner opening 206 may be about
0.5.+-.0.1, and the ratio Hh/ds between the length Hh of the sensor
holes and the sensor diameter ds may be about 1.6.+-.0.2.
Hence, when the ultrasonic sensor 210 is installed in the sensor
holes 202 and 204, as discussed above, the direct noise detected by
the receiver 204 is reduced from the conventional 100 mV to less
than 10 mV, and the controller 180 discriminates or is able to
discern between the signal reflected from the obstacles and the
direct noise because of the reduced amplitude of the direct
noise.
Although this embodiment has been described with respect to an
ultrasonic sensor as an example, the sensor unit is not limited to
the ultrasonic sensor but may include any sensor configured to
generate and receive a reflected signal.
Hereinafter, the procedure of discriminating or discerning between
a signal reflected by an obstacle and a direct noise of a cleaning
robot according to this embodiment will be described in more detail
with reference to FIGS. 7 to 11.
First, the transmitter 212 of the ultrasonic sensor 210 transmits
an ultrasonic wave, and a signal {circle around (s)} generated by
the transmitter 212 may be radiated, the radiation range thereof
being restricted by the sensor hole 202.
The signal {circle around (s)} radiated through the sensor hole 202
may be reflected from the obstacles 5 and 6 spaced away from the
case 110, and the reflected signal may pass through the sensor hole
204, where the receiver 214 may be installed, and then received by
the receiver 214. Part of the signal transmitted from the
transmitter 212 may generate a direct noise {circle around (3)},
which may be transmitted to the receiver 214 along the case
110.
Thus, when the signal reflected from the obstacles 5 and 6 and
received by the receiver 214 and the direct noise {circle around
(3)} received by the receiver 214 occur at the same time, the
controller 180 of the cleaning robot may detect the direct noise
{circle around (3)} by comparing the amplitudes of the direct noise
{circle around (3)} and the reflected signals {circle around (1)}
and {circle around (2)}.
That is, when a voltage of the signal received by the receiver 214
is less than a predetermined voltage, the controller 180 determines
that the received signal is a direct noise and ignores a signal of
less than the predetermined voltage in the procedure of determining
an obstacle.
Hence, when the obstacles 5 and 6 are detected through the receiver
214, even when different signals are received at approximately the
same time, the controller 180 can determine whether these received
signals are signals reflected from the obstacles or a signals
caused by direct noise.
In other words, in this embodiment, it is possible to discriminate
or discern a signal caused by the direct noise, and this leads to
the effect of dissolution of an obstacle un-measurable area that is
generated by the direct noise.
FIG. 15 is a cross sectional view illustrating a sensor hole of a
cleaning robot according to another embodiment of the present
invention.
The sensor holes 202 and 204 of the cleaning robot 100 according to
this embodiment may be provided so that they can be assembled (or
mounted) in the case 110.
Thus, the sensor holes 202 and 204, the sensor hole wall 203 and
the installation portion 207 may be assembled (or mounted) inside
the case 110.
More particularly, in the case that the sensor holes 202 and 204
are formed of such a structure that is assembled in the case 110,
as discussed above, the sensor holes 202 and 204 having the
ultrasonic sensor 210 assembled therein may be assembled (or
mounted) in the case 110, with the ultrasonic sensor 210 being
pre-assembled in the installation portion 207, instead of, e.g., an
assembly worker's installing the ultrasonic sensor 210 while
checking the position of the installation portion 207 inside the
case 110 during the manufacture of the cleaning robot 100. This
improves the assembling properties of the worker.
In addition, protrusions 203a may be formed on the sensor hole wall
203 and grooves 110a formed on the case 110 may be inserted and
assembled to each other. For example, the sensor holes 202 and 204
may be assembled in a downward direction from the upper side of the
case 110.
FIG. 16 is a cross sectional view illustrating a sensor hole of a
cleaning robot according to still another embodiment of the present
invention.
The sensor holes 202 and 204 of the cleaning robot according to
this embodiment are may be provided (or formed) as a protruding
part which protrudes to the outside of the case 110.
Part of the sensor hole wall 203 may protrude out of the outer side
of the case 110 and the orientation of the sensor hole 203 may be
improved.
Moreover, in the case that one of the sensor holes 202 and 204
protrudes to the outside of the case 110 and the other one is at
the same level as the outer surface of the case 110 or inserted
into the inside thereof, the orientation of a signal transmitted or
received through the sensor holes 202 and 204 can be further
improved by a height difference between the sensor holes.
Furthermore, the installation portion 207 of the sensor holes 202
and 204 may be formed (or provided) by enclosing the part
positioned inside the case 110 and so that the upper side or lower
side of the case 110 is opened.
Hereinafter, the other components are identical to those of the
first embodiment, so a detailed description thereof will be
omitted.
The present invention shall not be limited by the embodiments and
drawings disclosed in this specification but may be applicable by
those skilled in the art without departing from the scope of
protection of the true spirit of the invention.
Therefore, the present invention can dissolve (or eliminate) an
obstacle un-measurable area, which cannot be detected because of
the direct noise, by discriminating a signal caused by the direct
noise and a signal transmitted from the transmitter portion
depending on the amplitude of the signals among signals received by
the receiver portion in the sensor unit including the transmitter
portion and the receiver portion.
Additionally, the present invention can give orientation to the
range of the transmitter and receiver of the sensor unit by
inserting and installing the sensor unit including the transmitter
and the receiver portion into the sensor holes of the case, and can
easily compare a signal reflected from an obstacle and a signal
caused by the direct noise by reducing the amplitude of the signal
caused by the direct noise.
Moreover, the present invention provides a cleaning robot which
minimizes the signal of the direct noise and maximizes the slope of
the sensor holes.
Furthermore, the present invention minimizes the signal of the
direct noise and provides the ratio of the sensor diameter to the
diameter of the inner opening.
Further, the present invention minimizes the signal of the direct
noise and the ratio of the sensor diameter to the length of the
sensor holes.
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